Composition and process for light-weight surfactant products



United States Patent Office 3,425,948 Patented Feb. 4, 1969 Int. Cl.C11d 1/12 ABSTRACT OF THE DISCLOSURE Discrete, hollow detergentparticles are produced by subjecting a mass of finely divided solidalkali carbonate particles to a tumbling action by a continuously movingsurface such as a rotating pan tilted at an angle. During the tumblingon the moving surface, the alkali carbonate particles are sprayed withan acid reacting surface active agent material whereby said carbonatereacts with the surface active agent material neutralizing same andreleasing carbon dioxide gas. The release of the gas results in theformation of discrete, hollow particles of the detergent material.

This invention relates to a process for producing discrete, hollowdetergent particles.

In the prior art it has been customary to produce lightweight detergentmaterial by spray drying a slurry of the detergent material wherebydiscrete, hollow detergent particles are produced. The product in thisform is particularly desirable due to the fact that it dissolves rapidlyin water when used for washing or other applications.

It is well known to produce this type of product from alkyl, aryl oralkylaryl sulfonic acids or sulfuric acid esters made from alcohols orolefins which are neutralized with alkalies. According to prior artpractice, the sulfonic acids or sulfuric acid esters are dissolved inwater and neutralized with aqueous alkalies. After neutralization theadded water and water formed during the reaction is removed byevaporation or atomization in a spray dryer whereby the desireddiscrete, hollow bead-like detergent particles are formed.

Such practice possesses certain in herent disadvantages due to thenecessity of evaporating large quantities of water by heated aid whichinvolves substantial heating expense. In addition, the spray dryingapparatus is very large and involves a substantial capital investmentfor a given capacity. This practice has the further disadvantage thatrelatively expensive alkali hydroxides must be employed since the lessexpensive alkali carbonates lead to the formation of a disturbing foam.Also, as a result of the drying process, discoloration and partialdecomposition of the product may occur, and a substantial yield loss mayresult.

A procedure is known in the prior art according to which a sulfonic acidis neutralized by admixture with an alkali carbonate in the presence ofa small amount of water wherein the reactants are intimately contactedby kneading or stirring them together. However, a lightweight detergentproduct characterized by discrete, hollow, beadlike particles cannot beproduced by this method.

Accordingly, it is a purpose of this invention to provide a process forproducing discrete, hollow detergent particles without applying anexcessive amount of heat, wherein expensive space consuming,spray-drying equipment is not required, wherein less expensive alkalicarbonates may be employed and wherein discoloration and decompositionof the product is eliminated or substantially reduced.

In accordance with the instant invention, discrete, hollow detergentparticles are produced by subjecting a mass of ifinely divided solidalkali carbonate particles to a tumbling action by a continuously movingsurface such as the inner surface of a rotating cylinder or drum or arotating pan or disc tilted at an agle. During the tumbling on themoving surface, the alkali carbonate particles are sprayed with an acidreacting surface active agent material whereby said carbonate reactswith the surface active agent material neutralizing same and releasingcarbon dioxide gas. The release of the gas results in the formation ofdiscrete, hollow particles of the detergent material very similar to theparticles produced by spray drying. As a result of the tumbling action,a low bulk density is obtained which permits the formation of bubbles orindividual beads of the final product whereas stirring or mixing in akneading machine or similar devices does not permit such formation dueto a comparatively high bulk density. Further, the tumbling actionpermits quick release of the heat of reaction, thereby preventingdiscoloration due to excessive heat which is characteristic of prior artprocesses employing an alkali carbonate.

While the product produced in the tumbling apparatus may be completelydried by the heat of reaction requiring no additional heating or dryingoperation, in many instances it may be desirable to provide anadditional drying step to completely dry the particles. However, suchdrying may be carried out in a conventional rotary drumtype dryer andeven where a drying step is employed, less added heat is required tocompletely dry the product with the process of the instant invention ascompared with a spray drying process.

In general, the weight ratio of surface active agent material to alkalicarbonate should not exceed 2/1 since above that point a thick pastymaterial is obtained rather than hollow particles. On the other hand,there is no actual minimum ratio since where amounts of surface activeagent material are less than stoichiometric, you merely have a mixtureof the particles of detergent plus alkali carbonate. Since manydetergent formulations include alkali carbonates, such smaller ratios,e.g., as low as 1/100 surface active agent to carbonate, may be employedfor many purposes and a suitable product obtained.

In many cases it may be desirable to include in admixture with the acidreacting surface :active material an additional acid material which isnot a surface active agent material in order to react with the carbonateto produce greater quantities of 00 than would be produced by thereaction with the surface active agent material alone. Where these areemployed, it is preferred to have a weight ratio of the additional acidmaterial to the alkali carbonate of not greater than about 9/1.

It has been found desirable to maintain the temperature of the materialbeing sprayed below F. to avoid discoloration of the product due toheat. Where the acid reacting base stock is mixed with an additionalacid, generally the action is exothermic which would tend to drive thetemperature above the 140 F. maximum. Accordingly, in one preferredembodiment of this invention the additional acid and the surface activeagent material are mixed in a jacketed container such as a conventionalreaction kettle, etc., whereby the temperature is maintained below 140F. by controlling the rate of addition of the acid to the surface activeagent material or vice versa and by the use of cooling water or othercooling material flowing through the jacket of the kettle. This may alsobe accomplished by spraying the surface active agent material andadditional acid in two separate streams whereby they may contact in theair. In such instance the droplets of the reactants are surrounded bylarge volumes of air, thus preventing excessive temperature rise. Inaddition, they may be mixed in the conduit by means of a pipe mixingtype apparatus provided immediately ahead of the spraying device. Thismay comprise a simple venturi nozzle within the pipe for introducing theadded liquid or a jacketed perforated tube or sparger may be employedwherein one liquid goes through the perforated tube and the other liquidor liquids are introduced directly into the jacket surrounding theperforated tube. By mixing immediately ahead of the spraying device, thematerials are sprayed and contact the alkali carbonate particles in thepan before the reaction between the surface active agent and additionalacid proceeds far enough to release a substantial amount of the heat ofthe reaction whereby most of this heat of reaction is released in thepan to assist in drying the product in the pan.

Where desirable, the dry particles either coming directly from thetumbling apparatus or from a subsequent dryer, such as a conventionaldrum-type rotary dryer, may be cooled by passage through a conventionalcooling device, such as a rotating cylinder of drum wherein cooling airpasses over the material passing through the drum.

The liquid material may be sprayed onto the alkali carbonate particlesby any conventional spraying opening or device such as a nozzle,preferably a pnuematic type spray nozzle employing air under pressure.

The alkali carbonates suitable for use in the process of this inventionare preferably the carbonates, bicarbonates and sesquicarbonates ofsodium, potassium, and lithium. These carbonates may be used incommercial purity.

Where desired, alkali hydroxides such as sodium hydroxide, potassiumhydroxide, and lithium hydroxide may be included in the reaction mixturein lieu of a portion of the alkali carbonate to assist in neutralizingthe surface active agent material. However, there should always beenough alkali carbonate to provide a sufficient amount of CO gas to formthe desired hollow particles of the detergent. As previously stated, theweight ratio of surface active agent material to alkali carbonate shouldnot exceed 2/ 1 and, accordingly, there must be a sufficient amount ofalkali carbonate present to maintain an alkali carbonate to surfaceactive agent weight ratio of at least 1 to 2. The alkali hydroxide maybe added in many ways. For example, solid alkali hydroxide particles maybe mixed with the alkali carbonate particles, alkali hydroxide solutionmay be mixed with the surface active agent and/ or additional acid priorto spraying or alkali hydroxide in liquid from or solution may be addedto or sprayed onto the alkali carbonate.

The process of the present invention is applicable, for instance, toproduce alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates,sulfonated esters of fatty acids, sulfonated amides of fatty acids, andthe like.

Such detergents may be produced in the form of discrete, hollowdetergent particles from a variety of sulfonic acids or sulfuric acidesters. The alkylaryl sulfonic acids, which may be processed inaccordance with the instant invention, preferably contain 4 to 20 carbonatoms in their aliphatic side chains. The sulfonic acids may contain 1to 2 aromatic rings which, as the case may be, contain hydroxyl groupsas additional substituents. In the same way sulfuric acid esters may beprocessed which have been prepared from alcohols or olefins havingpreferably 12 to 18 carbon atoms. Also, alcohols or olefins of anycarbon number may be used for the preparation of the sulfuric acidesters. The sulfonic acids or sulfuric acid esters can include, forinstance, the sulfuric acid esters of lauryl, cetyl or tallow alcoholand, in general, any primary or secondary alcohol containing more than 8carbon atoms in its molecule. The sulfuric acid esters or sulfonic acidsto be used in this invention may be obtained from the correspondingalcohols or alkylaryl compounds by methods known to the art. These mayinclude the reaction with sulfuric acid, chlorosulfonic acid, S or othersulfonating agents. Typical sulfonic acids which may be employed aredodecyl benzene sulfonic acid, biologically soft linear alkyl benzenesulfonic acid, straight chain dodecyl benzene sulfonic acid, tridecylbenzene sulfonic acid, linear alkylate sufonic acid, linear alkylbenzene sulfonic acid, linear dodecyl benzene sulfonic acid, toluenesulfonic acid, xylene sulfonic acid, alkylaryl sulfonic acid, alkylnaphthalene sulfonic acid.

In addition to sulfonic acids or sulfuric acid esters, other acidreacting surface active agent materials may be employed, such asphosphate acids, e.g., complex organic (aliphatic) phosphate esters infree acid form, complex phosphate acids, alkylaryl phosphate acids;fatty acids including high molecular weight saturated fatty acids, e.g.,polyoxyethylated fatty acid, coconut oil fatty acid, low polyunsaturatedoleic acid, acetic acid salts of n-alkyl amines, oxyethylated fattyacid, a-sulfonated fatty acid, lanolin fatty acid, sulfated tall oilfatty acid, and pure lauric acid. Also, unsaturated organic acids suchas oleic acid, nonylphenoxy acetic acid, sulfated ricinoleic acid, lowpolyunsaturated oleic acid, organic amino-carboxylic aicd may beemployed. In addition, chelating acids may be employed, e.g., ethylenediamine tetraacetic acid, 1,2- diaminocyclohexane tetraacetic acid,ethylene glycol bis- (aminoethylether)tetraacetic acid, hydroxyethylethylene diamine triacetic acid, ethylene diaminedi(o-hydroxyphenyl)acetic acid, diethylene triamine pentaacetic acid,diaminoethyl ether tetraacetic acid, and nitrolo triacetic acid.

The additional acid materials which may be employed for reaction withthe carbonate in order to produce additional CO include the commonmineral acids such as sulfuric acid and phosphoric acid. In thisconnection it should be noted that often the readily available sulfonicacid and sulfuric acid ester materials generally include some freesulfuric acid. Other acids which may be employed are dicarboxylic acidssuch as oxalic acid, malonic acid, succinic acid, glutaric acid, adipicacid, pimelic acid, and suberic acid; saturated monocarboxylic acidssuch as formic acid, acetic acid, propionic acid, butyric acid, valericacid, caproic acid, capric acid, lauric acid, palmitic acid, stearicacid, orthoacetic acid, orthoformic acid, and enanthic acid; hydroxyacids such as glycolic acid, D- gluconic acid, lactic acid, glycericacid, D-galactic acid, citric acid, and pyruvic acid; unsaturatedmonocarboxylic acids such as oleic acid, linoleic acid, and ricinoleicacid; aromatic acids such as anthranilic acid, benzene sulfonic acid,benzoic acid, benzilic acid, l-naphthalene-8-sulfonic acid, naphthoicacid, and toluic acid; and unsaturated dicarboxylic acids such as maleicacid and fumaric acid.

The sulfonic acids, sulfuric acid esters or any of the otherabove-mentioned acid reacting surface active agent materials beingprocessed may be diluted with water.

The detergent material of the invention is readily formulated withalkaline, acid or neutral builder salts and auxiliary additives such asabsorbent siliceous compounds including calcium silicate, fullers earth,silica gel, divided silica, diatomaceous earth, and mixtures thereof,optical brighteners, anti-soil redeposition agents, for example,carboxymethylcellulose, anti-tarnishing agents such asmercaptobenzothiazole, benzotriazole, ethylene thiourea, and the like,agents to supply higher or smaller proportions of foam or suds asdesired, plasticizers, inert fillers, bleaches, solvents, dyes,perfumes, etc., in formulations in which those who practice the art ofcompounding cleaning compositions are very well versed.

The alkaline builder salts which can be employed in conjunction with thedetergent compositions of the present invention include, for example,alkali metasilicates, phosphates, including the molecularly dehydratedphosphates, carbonates and borates and, to a lesser extent, alkali metalhydroxide. Typical alkaline builder salts are sodium orthosilicate,sodium metasilicate, sodium carbonate, trisodium phosphate, sodiumtripolyphosphate, tetrasodium pyrophosphate, sodium hexametaphosphate,and sodium tetraborate. In most instances the above-described auxiliarymaterials may be added either directly to the inclined pan or rotatingdrum for agglomeration with the reactants or mixed with the liquid beingsprayed onto the carbonate particles.

This invention has the advantage of producing products as lightweight asthose made by spray drying with the added advantages of less dustiness,better storage characteristics, greater range of composition andsimpler, less costly equipment and process. The products made areparticularly suited for detergent applications like hand dishwashing,laundry, metal cleaning, and as intermediates for detergentformulations.

The process of the instant invention has several :advantages overproducing the product by spray drying. In the spray tower operation,essentially all of the product ingredients have to be added in theslurry, requiring elaborate mixing equipment for preparation andcumbersome equipment for spraying. This requirement greatly limits thechemical composition. Another advantage over spray drying is that anelaborate dust handling system is not required. It is estimated that theinstalled cost of the equipment for carrying out the process of theinstant invention is only about one-fifth to one-tenth of an equivalentspray tower installation. The process of this invention also has theadvantage of being more suitable for small scale production.

The following examples further illustrate the invention:

Examples axisof the shaft on which the pan is mounted is tilted at anangle of 72 to the horizontal. The pan is rotated at 18 rpm. by means ofa conventional electric motor and drive means driving the shaft, and thetumbling bed of alkali carbonate material is sprayed with a blend of thesurface active agent material and additional acid material, whereemployed, in the amounts indicated in the table below. With theexception of the sodium silicate in Examples 25-27, the ingredientsindicated as Other Materials" in the table are introduced into theinclined pan with the alkali carbonate material. Where sodium silicateis introduced with the alkali carbonate, it is in the form of anhydroussodium metasilicate fines. The sodium silicate in Examples 25-27 is1:3.25 Na O:SiO ratio by Weight and is added as an aqueous solutioncontaining by weight 8.9 percent Na O, 29.0 percent Si0 and 62.1 percentwater. In Examples 1-22, the additional acid and the surface activeagent material are mixed together in a conventional, jacketed mixingtank. Due to the heat liberated during mixing, cooling water iscirculated in the jacket whereby the temperature of the mixture ofsurface active agent and additional acid is kept from rising above 140F. Stainless steel type 316 is suitable for such mixing tank and for anypiping or conduits employed for conducting the material from the mixingtank to the spray nozzle as well as for the spray nozzle itself. Monelmetal may also be employed, however, this is considerably moreexpensive.

In Examples 24-27, the liquid materials are piped directly to the spraynozzle through separate pipes. The fluids are then mixed immediatelypreceding the spray nozzle in a pipe mixer or sparger type apparatuswhich, as previously described, is simply a perforated tube surroundedby an outer jacket. The additional acid material is injected through theperforated pipe while the sodium silicate solution and the surfaceactive agent base stock are introduced directly into the jacketsurrounding the perforated pipe or tube.

The agglomerated particles discharged from the continuously movingsurface of the tumbling apparatus of all examples, except 10 and 19, aredried by one pass through a direct fired rotary dryer, 8 feet long and22 inches in diameter, rotating at 3 r.p.m. and having a slope of A inchper foot, the inlet air at 310 F. entering the dryer with the product inparallel current flow. The product is then cooled to room temperature ina conventional rotating drum cooler, 2 feet in diameter, 8 feet long androtating at 3 r.p.m. The agglomerated particles produced in Examples 10and 19 are not dried or cooled. The finished product comprises smallbeads of detergent material having a bulk density of about 35 pounds percubic foot and resembles a spray dried product. However, it is superiorto a spray dried product in that it is less dusty, more free flowing andless sensitive to pressure compaction which provides better storageproperties.

TABLE Alkali carbonate Surface active Additional acid Other materials,parts by weight agent, base stock Ex. Percent No. Parts Parts surfaceParts Kind by Desigby active Kind by NaCl STPP Sodium ClTSP TSPP weightnation weight agent in weight silicate z slurry 57. 5 1 22. 2 12. 8H1804 (98%)- 20. 3 34.0 2 71. 7 41. 6 H2804 (98%) 31. 5 47. 6 2 30. 317. 6 H28 04 (98%) 50. 0 14.8 2 1s. 7 10. 8 H2804 (98%)-- 19. 1 34. 0 230. 3 17. 6 H2804 (98%)-- 35. 1 97. 7 2 30.0 17. 4 H2804 (98%) 56. 9 66.4 2 27. 7 16. 1 H1804 (98%)-- 47. 2 55. 6 2 30. 0 17.4 H2804 (98%)-- 73.6 21.0 3 10.0 5. 8 H2804 (98% 29. 1 33.2 4 32.0 18. 6 H2804 (98% 30. 757. 5 5 22. 3 12.9 H2804 (98% 53. 3 27. 7 6 40. 5 23. 5 H280 (98%)- 30.8 42. 7 7 35. 4 20. 5 H2804 (98% 43. 5 54. 1 8 12. 6 7. 3 H280 (98% 56.6 27. 6 9 12. 0 6. 9 H2804 (98%)-. 27.4 51. 0 10 30.0 17. 4 H2804(98%)-- 47. 2 48. 4 2 72. 5 42. 0 H3PO4 29. 1 45. 8 2 72. 5 42.0 54. 537. 5 2 72. 5 42. 0 42. 5 42. 7 2 36. 3 21. 0 Citric acid 79. 0 13. 8 236. 3 21. 0 Oleic acid".-- 73. 3 29. 0 2 36. 3 21. 0 Benzoic acid. 66. 948. 0 2 72. 0 42. 0 34. 3 2 71. 7 41. 6 H2804 (98%)- 32. 3 47. 8 2 31. 218. 1 H2804 (98%)-- 48. 2 7. 9 15. 1 2 18. 7 10. 8 HZSO4 (98%)- 19. 313. 2 34. 2 2 30. 3 17. 6 H2804 (98%)-- 35. 3 7. 9 24. 2 2 72.5 42. 0HzSO (98%)-- 52. 3 24.2 sodium hydroxide The surface active agentmaterials indicated by the numbers ranging from 1 to 10, under theheading Designation, in the above table are as follows:

(1) A dodecyl benzene sulfonic acid having the formula C16H3003S.

(2) A linear alkyl benzene sulfonic acid having 12 to 13 carbon atoms inthe alkyl group.

(3) An alkylaryl ether.

(4) A tridecyl benzene sulfonic acid having the formula C19H3203S.

(5) A toluene sulfonic acid having the formula (371 130 8.

(6) An alkyl naphthalene sulfonic acid having the formula C H O S.

(7) An octyl diphenyl phosphoric acid having the formula (32 11 7041 (8)A coconut oil fatty acid having the formula CH3005S.

(9) A sulfated ricinoleic acid having the formula C H O S.

(10) An ethylene diamine tetraacetic acid having the formulaC1OH1ZN2NZ4OB.

In the table above, the Other Materials by abbreviated notation are asfollows:

STPP Sodium tripolyphosphate.

designated ClTSP Chlorinated trisodium phosphate.

TSPP Tetrasodium pyrophosphate.

It is to be understood that various changes and modification may be madein the foregoing invention without departing from the spirit of theinvention and scope of the appended claims.

What is claimed is:

1. A process for producing discrete, hollow detergent particlescomprising the steps of subjecting a mass of finely divided solid alkalimetal carbonate particles to a tumbling action by a continuously movingsurface and spraying said particles with acid reacting surface activeagent material wherein said acid reacting surface active agent materialis selected from the group consisting of alkylaryl sulfonic acids whichcontain from 4 to carbon atoms in their aliphatic side chains and one ortwo aromatic rings, sulfuric acid esters prepared from alcohols orolefins having from 12 to 18 carbon atoms, organic phosphate esters,organic phosphate acids, higher molecular weight saturated fatty acids,unsaturated fatty acids, sulfated and amino unsaturated fatty acids, andchelating acids, whereby said carbonate reacts with said surface activeagent material releasing carbon dioxide gas, the release of said gasresulting in the formation of said hollow particles of the detergentmaterial.

2. The process of claim 1 wherein alkali metal hydroxide is includedwith the reaction components.

3. The process of claim 1 wherein the weight ratio of said surfaceactive agent material to alkali metal carbonate is not greater thanabout 2/1.

4. A process for producing discrete, hollow detergent particlescomprising the steps of subjecting a mass of finely divided solid alkalimetal carbonate particles to a tumbling action by a continuously movingsurface and spraying said particles with acid reacting surface activeagent material and additional acid material wherein said acid reactingsurface active agent material is selected from the group consisting ofalkylaryl sulfonic acids which contain from 4 to 20 carbon atoms intheir aliphatic side chains and one or two aromatic rings, sulfuric acidesters, prepared from alcohols or olefins having from 12 to 18 carbonatoms, organic phosphate esters, organic phosphate acids, highermolecular weight saturated fatty acids, unsaturated fatty acids,sulfated and amino unsaturated fatty acids, and chelating acids, andsaid addi tional acid material is selected from the group consisting ofsulfuric acid, phosphoric acid, unsubstituted aliphatic dicarboxylicacid having from 2 to 10 carbon atoms, unsubstituted aliphaticmonocarboxylic acids having from 1 to 18 carbons atoms, aliphatic andaromatic hydroxy acids, and unsaturated carboxylic and sulfonic aromaticacids, whereby said carbonate reacts with said surface active agentmaterial and with said additional acid material releasing carbon dioxidegas, the release of said gas resulting in the formation of said hollowparticles of the detergent material.

5. The process of claim 4 wherein the weight ratio of said surfaceactive agent material to said alkali metal carbonate is not greater thanabout 2/1 and the weight ratio of said additional acid to said alkalimetal carbonate is not greater than about 9/1.

6. The process of claim 5 wherein said surface active agent material isa sulfonic acid and said additional acid is a mineral acid.

7. The process of claim 5 wherein said surface active agent material isa sulfonic acid and said additional acid is sulfuric acid.

8. The process of claim 5 wherein said carbonate is sodium carbonate.

9. The process of claim 5 wherein said carbonate is sodium bicarbonate.

10. The process of claim 5 wherein said carbonate is potassiumcarbonate.

11. The process of claim 5 wherein said surface active agent materialand said additional acid are mixed in a mixing vessel prior to spraying.

12. The process of claim 5 wherein said surface active agent materialand said additional acid are mixed in a conduit immediately prior tospraying.

References Cited UNITED STATES PATENTS 8/1965 Habicht et al 252-13812/1965 McKenna et al 252l38 U.S. C1.X.R.

